JP2014079688A - Phosphorus recovery system and phosphorus recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphorus recovery system and phosphorus recovery method which can favorably recover phosphorus with less impurities.SOLUTION: A phosphorus recovery system 1 is a system that recovers phosphorus from phosphorus-containing wastewater, and at least includes a screen residues removal device 3, a membrane filtration device 5, an adsorption device 9, and a recovery device 11.

Description

  The present invention relates to a phosphorus recovery system and a phosphorus recovery method capable of recovering phosphorus from wastewater generated from sewage, food factories, chemical factories, households, and water containing phosphorus such as rivers and lakes. .

  Conventionally, phosphate ions in waste water are adsorbed on an adsorbent, and an alkaline solution is passed through the adsorbent that has adsorbed phosphate ions to desorb phosphate ions from the adsorbent to the alkaline solution, thereby desorbing phosphate ions. A method is known in which lime is added to an alkaline solution to precipitate a phosphate compound containing calcium phosphate, the phosphate compound is subjected to solid-liquid separation, and the solid-liquid separated alkaline solution is reused for the next desorption (for example, Patent Document 1).

JP 63-236588 A

  The conventional method has a problem that the recovered phosphate compound such as calcium phosphate contains a large amount of impurities such as iron, aluminum, and silica contained in the waste water. When a phosphoric acid compound containing a large amount of these impurities is used as a raw material for a phosphoric acid production plant, for example, there may be a problem that the quality such as the purity and crystallinity of the phosphoric acid and gypsum produced are deteriorated.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a phosphorus recovery system and a phosphorus recovery method that can recover phosphorus with less impurities.

  As a result of diligent research to solve the above problems, the inventors of the present invention have a specific apparatus configuration, and by treating phosphorus-containing water with this apparatus, impurities such as iron, aluminum, and silica are contained in the phosphorus-containing water. The inventors have found that a small amount of a phosphoric acid compound can be recovered, and have made the present invention.

  That is, the phosphorus recovery system according to the present invention is a phosphorus recovery system that recovers phosphorus from phosphorus-containing water, and includes at least a residue removing device, a membrane filtration device, an adsorption device, and a recovery device.

  In one embodiment, the adsorption device has an adsorbent containing an inorganic ion adsorbent.

  In one embodiment, the adsorption device includes adsorbent cleaning means for cleaning the adsorbent with an acidic aqueous solution.

  In one embodiment, the recovery device includes a precipitation tank that precipitates a phosphate compound from phosphate ions in the desorption liquid, and the precipitation tank includes stirring means for stirring the desorption liquid.

  In one embodiment, the recovery device includes solid-liquid separation means that separates the precipitate in the desorption liquid and the desorption liquid by a solid-liquid separation by a filter press method.

  The phosphorus recovery method according to the present invention is a phosphorus recovery method for recovering phosphorus from phosphorus-containing water, and includes at least a residue removal operation, a membrane filtration operation, an adsorption operation, and a recovery operation.

  In one embodiment, the adsorption operation includes a step of adsorbing phosphate ions in phosphorus-containing water to an adsorbent containing an inorganic ion adsorbent.

  In one embodiment, the recovery operation includes a step of desorbing phosphate ions from the adsorbent by a desorption solution, a step of adding a precipitating agent to the desorption solution, and a step of stirring the desorption solution.

  In one embodiment, the adsorption operation includes a step of washing the adsorbent with an acidic aqueous solution.

  In one embodiment, the recovery operation includes a step of solid-liquid separation of the precipitate in the desorption liquid and the desorption liquid by a filter press method.

  According to the present invention, phosphorus can be satisfactorily recovered from phosphorus-containing water. In particular, in the present invention, a phosphoric acid compound with few impurities such as iron, aluminum and silica can be recovered.

It is a figure which shows the phosphorus collection | recovery system which concerns on one Embodiment. It is a table | surface which shows the result of an Example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a diagram illustrating a phosphorus recovery system according to an embodiment. As shown in FIG. 1, the phosphorus recovery system 1 includes a residue removing device 3, a membrane filtration device 5, a storage tank 7, an adsorption device 9, and a recovery device 11. In addition, the phosphorus collection | recovery system 1 which implement | achieves the phosphorus collection | recovery method concerning this invention should just be provided with the residue removal apparatus 3, the membrane filtration apparatus 5, the adsorption | suction apparatus 9, and the collection | recovery apparatus 11.

  The screen residue removal device 3 is a device that performs screen residue removal operations such as a screening method, an agglomeration method, a precipitation separation method, a flotation separation method, and a sand filtration method, although not particularly limited. Screening methods include bar screens, drum screens, and vibration screens. The aggregation method includes a method using an inorganic flocculant and a method using an organic flocculant. Precipitation separation methods include sedimentation separation and precipitation concentration. Examples of sedimentation separation include natural sedimentation separation, inclined sedimentation separation, and coagulation sedimentation separation. The floating separation method includes a bubble contact method and a bubble precipitation method. Sand filtration methods include rapid filtration and slow filtration.

  The system of the screen residue removal device 3 is appropriately selected according to the type and amount of screen residue and suspended solids (hereinafter referred to as SS (Suspended Solid)) in the phosphorus-containing waste water (phosphorus-containing water). In particular, when the phosphorus-containing wastewater contains a large amount of residue and SS, such as sludge-treated return water, a precipitation separation method and a screening method are preferable. In particular, the drum-type screen is effective in removing the residue and can remove colloidal silicon adhering to the residue together with the residue, so that the silicon that is an impurity of the recovered phosphate compound can be reduced. More preferred. Although the hole diameter of a drum type screen is not specifically limited, About 0.5 mm-2 mm are preferable.

  The membrane filtration device 5 is not particularly limited, and is a device that includes an ultrafiltration membrane, a microfiltration membrane, a dialysis membrane, and the like, and performs a membrane filtration operation. Although the form of a film | membrane is not specifically limited, A flat film | membrane, a hollow fiber, a pleat, a tube shape etc. are mentioned. The membrane is preferably a hollow fiber ultrafiltration membrane or a microfiltration membrane in terms of filtration speed and filtration accuracy.

  The material of the filtration membrane is not particularly limited. There are many types such as ethylene vinyl alcohol copolymer polymer, polyolefin polymer and ceramics. Polyacrylonitrile, polysulfone, polyvinylidene fluoride, polyethylene, polypropylene, and ceramics are particularly preferable in terms of excellent acid resistance and alkali resistance.

  The membrane filtration device 5 having the above configuration can remove impurities that are finer than conventionally used sand filtration and the like. Therefore, the phosphorus recovery system 1 can increase the purity of phosphorus contained in the recovered phosphate compound. The membrane filtration device 5 is preferably applied with an ultrafiltration membrane because of its high impurity removability, but is preferably applied with a microfiltration membrane because of severe clogging caused by suspended matter in the waste water.

  The form of the membrane module is not particularly limited, and examples thereof include a pressure type and an immersion type. In particular, the membrane module is preferably of the immersion type when the phosphoric acid-containing wastewater contains a large amount of SS, such as sludge-treated return water. In this case, the filtration flow rate is preferably 0.1 m / day to 1 m / day, although it depends on the SS concentration. Further, the SS concentration in the tank is preferably 1000 mg / L to 10000 mg /.

  The storage tank 7 is a tank that temporarily stores the phosphorus-containing wastewater filtered by the membrane filtration device 5. The storage tank 7 supplies phosphorus-containing wastewater to the adsorption device 9.

  Although the adsorption device 9 is not particularly limited, the adsorption device 9 usually has a configuration in which an adsorbent is filled in a container, and is an apparatus in which an adsorption operation is performed. The shape of the container and the shape of the packed bed of the adsorbent are not particularly limited as long as the adsorbent and the phosphorus-containing drainage can contact each other, and examples thereof include a cylindrical shape, a column shape, a polygonal column shape, and a box shape. it can. These containers are preferably provided with a solid-liquid separation mechanism that prevents the adsorbent from flowing out of the container, such as a pan and a mesh. The material of the container is not particularly limited, and examples include stainless steel, glass fiber reinforced plastic, glass, and various plastics. In consideration of acid resistance, the inner surface may be made of rubber or fluororesin lining.

  The contact method between the adsorbent and the phosphorus-containing wastewater is not particularly limited as long as the adsorbent and the phosphorus-containing wastewater can contact each other. A method in which an adsorbent is filled in an adsorption tower and a phosphorus-containing wastewater is passed through and contacted is preferable because the high contact efficiency that is characteristic of the adsorbent can be sufficiently extracted. When the adsorbent packed bed is a fixed bed, the vertical, vertical, or downward flow of the cylindrical, polygonal or box-type adsorbent packed bed, or the horizontal flow of the packed bed Or an external pressure method in which water is passed through the cylindrical adsorbent packed bed from the outer circumferential direction to the inner cylinder, and an internal pressure method in which water is passed in the opposite direction. The packed bed of adsorbent may be a fluidized bed system.

  As the adsorption device 9, a merry-go-round device can be adopted. The merry-go-round method is to place a plurality of adsorption towers in series and conduct water, and if the adsorption capacity of the adsorption tower in the previous stage decreases, the adsorption tower stops flowing and the adsorption tower located in the latter stage Through the front. In the merry-go-round method, treated water with continuous and stable water quality is realized by sequentially passing water through the adsorption tower at a time difference from the previous stage.

The speed at which the phosphorus-containing wastewater is passed through the adsorbent is not particularly limited, but if it is slow, the necessary amount of adsorbent increases. On the other hand, when the speed is high, the efficiency of phosphorus removal becomes worse and the pressure loss becomes higher. The preferred liquid passing speed depends on the phosphorus concentration in the phosphorus-containing wastewater, but is preferably 1h ^{−1 to} 30h ^{−1 in} terms of space velocity (hereinafter referred to as SV (Space Velocity)).

  Although the adsorbent used for the adsorption apparatus 9 of this embodiment is not specifically limited, The adsorbent containing an inorganic ion adsorbent is preferable. In particular, the adsorbent described in Japanese Patent No. 4671419 is more preferable because of its high adsorption rate.

  The inorganic ion adsorbent used in the present embodiment refers to an inorganic substance that exhibits an ion adsorption phenomenon. For example, natural products include zeolite, montmorillonite, various minerals, kaolin minerals with a single layer lattice of aluminosilicate, muscovite with a two-layer lattice structure, sea green stone, Kanuma soil, pyrophyllite, talc It is represented by feldspar, zeolite and the like having a three-dimensional framework structure. In the composite system, there are metal oxides, and the main ones are metal oxides, polyvalent metal salts, insoluble heteropolyacid salts, insoluble hexacyanoferrates, and the like.

  As the inorganic ion adsorbent contained in the adsorbent of the present embodiment, hydrated titanium oxide, hydrated zirconium oxide, hydrated tin oxide, and hydrated cerium oxide from the viewpoint of excellent phosphate ion adsorption performance. Metal oxide selected from the group consisting of hydrated lanthanum oxide, hydrated yttrium oxide, titanium, zirconium, tin, cerium, lanthanum and yttrium, and a metal element selected from the group consisting of aluminum, silicon and iron And at least one metal oxide selected from the group consisting of activated alumina. In particular, hydrated zirconium oxide, hydrated cerium oxide, and hydrated lanthanum oxide are more preferable because of high ion selectivity to phosphoric acid and a high phosphorus content of the recovered phosphorus compound.

  In the adsorbent used in the present embodiment, the material for supporting the inorganic ion adsorbent is not particularly limited, but an organic polymer resin is preferable. Examples of organic polymer resins include polysulfone polymers, polyvinylidene fluoride polymers, polyvinylidene chloride polymers, acrylonitrile polymers, polymethyl methacrylate polymers, polyamide polymers, polyimide polymers, cellulose polymers, and ethylene vinyl. There are many types such as alcohol copolymer polymers. In particular, ethylene vinyl alcohol copolymer, polyacrylonitrile, polysulfone, and polyvinylidene fluoride are preferable because they are non-swellable in water, biodegradable, and easy to produce, and also have both hydrophilicity and chemical resistance. In this respect, an ethylene vinyl alcohol copolymer (hereinafter referred to as EVOH) is preferable.

  The adsorbent of this embodiment desorbs the adsorbed phosphate ions by contacting with the desorption liquid. The adsorbent can adsorb phosphate ions again by treating with an acidic aqueous solution. Therefore, the adsorption device 9 includes an adsorbent cleaning means for cleaning the adsorbent with an acidic aqueous solution. By reusing the adsorbent, not only the cost can be reduced but also the waste can be reduced. In particular, the adsorbent of the present embodiment is suitable for repeated use because of its excellent durability.

  The desorption liquid is preferably alkaline, and the pH of the alkaline liquid can desorb phosphate ions from the adsorbent as long as the pH is 10 or more, but is preferably pH 12 or more, more preferably pH 13 or more. The alkali concentration is in the range of 0.1 wt% to 30 wt%, more preferably in the range of 0.5 wt% to 20 wt%. If the alkali concentration is lower than 0.1 wt%, the desorption efficiency is lowered, and if the alkali concentration is higher than 30 wt%, the chemical cost of the alkali tends to increase.

The liquid passing rate of the desorption liquid is not particularly limited, but is usually preferably in the range of SV 0.5 to 15 h- ¹ . If the flow rate is lower than SV0.5h- ¹ , the desorption time tends to be long and inefficient, and if the flow rate is higher than SV15h- ¹ , the contact time between the adsorbent and the aqueous alkaline solution is shortened. The desorption efficiency tends to decrease.

  The type of the desorption liquid is not particularly limited, and usually an aqueous solution of an inorganic alkali such as an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or ammonium hydroxide, and an organic amine is used. Among them, it is particularly preferable to use sodium hydroxide from the viewpoint of cost.

  The porous molded body in the column after the desorption operation is alkaline, and as it is, the ability to adsorb phosphate ions in the phosphorus-containing wastewater is low. Then, operation which returns pH in a column to a predetermined value is performed using acidic aqueous solution.

The acidic aqueous solution is not particularly limited, but an aqueous solution such as sulfuric acid or hydrochloric acid is used. The concentration may be about 0.001 to 10 wt%. If the concentration is lower than 0.001 w%, a large amount of water volume is required until the activation is completed, and if the concentration is higher than 10 wt%, there is a risk of problems in handling the acidic aqueous solution. . The liquid passing speed is not particularly limited, but is usually preferably in the range of SV 0.5 to 30 h ⁻¹ . If the liquid flow rate is smaller than SV0.5h- ¹ , the liquid flow time tends to be long and inefficient, and if the liquid flow rate is larger than SV30h- ¹ , the contact time between the adsorbent and the acidic aqueous solution is short. The neutralization efficiency tends to decrease.

  In the phosphorus collection | recovery system 1, since the impurity adhering to adsorption agent can be further wash | cleaned by neutralizing adsorption agent by acidic aqueous solution, the phosphorus content of the collection | recovery phosphate compound can be increased.

  The recovery device 11 is a device in which a recovery operation for recovering phosphate ions in the desorption solution as a phosphate compound is performed. The recovery device 11 includes a precipitation tank 13 and a solid-liquid separator (solid-liquid separation means) 15.

  In the precipitation tank 13, a precipitation operation is performed. The precipitation operation is not particularly limited as long as the phosphate compound can be precipitated from the desorption solution, but the solution is concentrated by evaporating the solvent from the solution in which the desorbed phosphate ions are dissolved, or cooled to a concentration higher than the saturation solubility. To precipitate crystals by increasing the concentration, or to precipitate crystals with low solubility by reaction by adding a precipitant, or to deposit a phosphate compound on the surface of the core material by contacting with the core material Is preferred. The operation of adding a precipitating agent to precipitate crystals is simple and more preferable.

  In the precipitation operation of the present embodiment, there is no particular limitation on the operation even when a deposition agent is added. In this case, the precipitation tank 13 includes an addition operation means (not shown) for adding a precipitation agent such as a pump and a hopper, and a flow path (not shown) connecting the precipitation tank 13 and the addition operation means. preferable. The precipitation tank 13 preferably includes stirring operation means (stirring means) such as a stirring blade and a pump for stirring the inside of the tank. In the precipitation tank 13, since the precipitation reaction proceeds sufficiently by providing the stirring operation means, the phosphorus content in the recovered phosphoric acid compound can be increased.

  Examples of the precipitating agent include polyvalent metal hydroxides. In the hydroxide of a polyvalent metal, a metal salt combines with phosphorus to form a precipitate. Further, since the hydroxide becomes an alkali source of the desorption liquid, a closed system can be obtained by collecting and recycling the regenerated liquid. Specific examples include calcium hydroxide, aluminum hydroxide, and magnesium hydroxide. In particular, calcium hydroxide is preferable in terms of cost. Further, when the recovered phosphate compound is used as a fertilizer, magnesium hydroxide is preferable because magnesium has a fertilizer effect.

The properties of the precipitating agent are not particularly limited, such as powder, slurry, and liquid, but slurry or liquid is preferred in consideration of operability and reaction uniformity. When the phosphate ion desorbed in the desorption solution is present as sodium phosphate, the alkaline solution is regenerated according to the following reaction formula when calcium hydroxide is used as the deposition agent. At the same time, phosphate ions are precipitated as hydroxyapatite, a kind of calcium phosphate. The precipitated calcium phosphate is recovered by a solid-liquid separation operation described later, and can be recycled as a fertilizer or a substitute for phosphate ore.
6Na ₃ PO ₄ + 10Ca (OH) ₂ → Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ + 18NaOH

  The addition amount of the polyvalent metal hydroxide is not particularly limited, but is 1 to 4 times the equivalent amount of the target phosphate ion. When the addition amount is 1 times equivalent or less, the precipitation removal efficiency is low, and when it exceeds 4 times equivalent, the removal efficiency is hardly changed. When removing the precipitate, the pH is preferably 6 or more. Further, considering that the alkaline aqueous solution is recovered and reused, it is preferably maintained at pH 12 or more, preferably at pH 13 or more. If the pH during the precipitation treatment is lower than 6, the solubility of the precipitate increases and the precipitation efficiency decreases. When removing the precipitate, in addition to the metal hydroxide, an inorganic flocculant such as aluminum sulfate or polyaluminum chloride, or a polymer flocculant may be used in combination.

  In the solid-liquid separator 15, a solid-liquid separation operation between the desorption liquid and the precipitate is performed. The solid-liquid separation operation of this embodiment is not particularly limited, but usually, sedimentation separation, centrifugal separation, belt press machine, screw press machine, membrane separation method and the like can be used. In particular, the filter press method and the membrane separation method are preferred in that the installation area is small and clear filtered water can be obtained. Since the recovered phosphoric acid compound has a low water content and can be washed at the same time, the purity of the recovered phosphorus can be further increased, and the filter press method is more preferable. The desorption liquid separated by the solid-liquid separator 15 is stored in a desorption liquid tank (not shown). The desorption liquid in the desorption liquid tank is used again in the desorption operation.

  The present embodiment will be described in more detail with reference to the following examples, but the present embodiment is not limited to the following examples.

[Example 1]
The residue removing device used was a drum type screen, and the hole diameter of the drum was 1 mm. The membrane filtration apparatus used was an immersion type MF membrane filtration system, and the membrane was hollow fiber. The nominal pore diameter of the hollow fiber membrane was 0.1 μm. The adsorption device used was composed of an adsorption tower filled with an adsorbent. This adsorbent is composed of hydrated zirconium oxide and EVOH, and is produced by the method of Example 1 of Japanese Patent No. 4907585. Specifically, the adsorbent is a spherical particle having a particle size of about 0.6 mm. The recovery device was composed of a precipitation tank and a solid-liquid separator, and the solid-liquid separator used was a filter press type.

  The phosphorus-containing wastewater enters a storage tank through a residue removal device and a membrane filtration device. Phosphorus ions are removed from the phosphorus-containing wastewater supplied from the storage tank by the adsorption device. Thereby, treated water is obtained. Phosphate ions removed by the adsorption device are desorbed from the adsorbent by a desorption solution (1% aqueous sodium hydroxide solution) and taken into the recovery device. By adding calcium hydroxide to the desorption liquid taken into the precipitation tank, a phosphate compound containing calcium phosphate is precipitated. The desorption liquid containing a phosphoric acid compound is separated into a phosphoric acid compound and an alkaline desorption liquid by a solid-liquid separator. This desorption solution can be used again to desorb phosphate ions from the adsorbent in the adsorber. Further, since the adsorbent after desorption is alkaline, it is neutralized with an aqueous sulfuric acid solution, and the adsorbent can adsorb phosphate ions again.

  Subsequently, a phosphorus recovery method using the phosphorus recovery system will be described.

  As the phosphorus-containing wastewater, the sludge treated with the activated sludge method and the sedimentation treatment in the wastewater treatment facility of the food factory was subjected to treatment such as digestion and dehydration, and sludge treated return water generated by this was used. As for the water quality of this phosphorus-containing wastewater, orthophosphoric phosphorus (hereinafter referred to as OP) was 100 mg / L, pH was 8.5, and SS was 500 mg / L, and many fibrous residues were observed. The drainage in the storage tank after draining phosphorus-containing wastewater and passing through the residue removing device and the membrane filtration device had OP of 100 mg / L and pH of 7.5, and residue and SS were hardly seen. At this time, the membrane filtration apparatus was operated with a filtration flow rate of 0.3 m / day and an SS concentration in the tank of about 3000 mg / L.

As for the waste water in the storage tank, the OP of the treated water from which phosphorus was removed through the adsorption device was 1 mg / L or less. At this time, the water flow rate in the adsorbent was SV10h- ¹ . When the OP of treated water exceeded 1 mg / L, it was determined that the adsorbent had broken through, and the adsorption operation was interrupted. The desorption liquid was passed through the adsorbent of the adsorption tower at SV20h- ¹ for 30 minutes to desorb phosphate ions. Slaked lime was added to the desorption liquid in the precipitation tank and stirred for 30 minutes.

  The amount of calcium hydroxide added was 3 in terms of the molar ratio of calcium in calcium hydroxide to phosphate ions in the desorption solution. After stirring, the desorption liquid was applied to a solid-liquid separator to separate the desorption liquid and the phosphoric acid compound. By passing dilute sulfuric acid through the phosphate compound in the filter press, neutralization and excess calcium hydroxide were removed. The phosphoric acid compound demolded from the filter press was obtained as a cake having a water content of 50%. This cake was dried at 110 ° C. with a dryer to obtain a phosphoric acid compound. The composition was determined by chemical analysis of this phosphate compound. The analytical value of the phosphoric acid compound is shown in FIG.

[Example 2]
A phosphorus recovery system similar to that in Example 1 was used except that the debris removing device was a natural sedimentation separation instead of the drum type screen. The hydraulic retention time for natural sedimentation separation was 1 hour. Except for this, phosphorus was collected under the same operating conditions as in Example 1. The analytical value of the phosphoric acid compound is shown in FIG.

[Example 3]
Phosphorus recovery was performed in the same manner as in Example 1, except that the adsorbent was replaced with hydrated zirconium oxide and EVOH, and an adsorbent composed of activated alumina and EVOH was used. Carried out. The analytical value of the phosphoric acid compound is shown in FIG. In Example 3, it was confirmed that the phosphorus content in the recovered phosphoric acid compound was significantly low, and the impurity aluminum was greatly increased.

[Example 4]
Phosphorus recovery was carried out in the same manner as in Example 1, except that the neutralization in the filter press was changed to diluted hydrochloric acid instead of diluted sulfuric acid, and the same phosphorus recovery system as in Example 1. The analytical value of the phosphoric acid compound is shown in FIG. In Example 4, it was confirmed that the calcium content in the recovered phosphate compound decreased and the phosphorus content increased.

[Example 5]
Phosphorus recovery was carried out by the same operation as in Example 1 using the same phosphorus recovery system as in Example 1 except that a bar screen was used instead of the drum screen as the residue removing device. The analytical value of the phosphoric acid compound is shown in FIG. In Example 5, it was confirmed that the impurity content in the recovered phosphate compound was increased.

[Comparative Example 1]
The same phosphorus recovery system as in Example 1 was used except that there was no residue removal device. The sludge treated return water, which is phosphorus-containing wastewater, was directly introduced into the membrane filtration apparatus, and phosphorus was collected under the same operating conditions as in Example 1 except for this. The analytical value of the phosphoric acid compound is shown in FIG.

  As shown in FIG. 2, in Example 1-5 and Comparative Example 1, the difference in the content of phosphorus and calcium in the phosphoric acid compound is not so large, but if there is a residue removing device, impurities (iron, aluminum) It has been confirmed that the amount of silicon) is reduced as a whole, and further, when a drum-type screen is used as a residue removing device, the amount of silicon is greatly reduced. This is considered to remove colloidal silicon adhering to the residue by removing the residue.

  It can be recovered as a phosphate compound with less impurities by removing phosphorus from wastewater generated from sewage, food factories, chemical factories, households, and phosphorus-containing water such as rivers and lakes.

  DESCRIPTION OF SYMBOLS 1 ... Phosphorus collection | recovery system, 3 ... Debris removal apparatus, 5 ... Membrane filtration apparatus, 9 ... Adsorption apparatus, 11 ... Recovery apparatus.

Claims (12)

A phosphorus recovery system for recovering phosphorus from phosphorus-containing water,
A phosphorus recovery system comprising at least a residue removing device, a membrane filtration device, an adsorption device, and a recovery device.   The phosphorus collection system according to claim 1, wherein the residue removing device is a drum type screen.   The phosphorus recovery system according to claim 1, wherein the adsorption device has an adsorbent containing an inorganic ion adsorbent.   The phosphorus recovery system according to claim 3, wherein the adsorption device includes an adsorbent cleaning unit that cleans the adsorbent with an acidic aqueous solution. The recovery device includes a precipitation tank for depositing a phosphate compound from phosphate ions in the desorption liquid,
The phosphorus collection system according to claim 3 or 4, wherein the precipitation tank includes a stirring unit that stirs the desorption liquid.   The phosphorus recovery system according to claim 5, wherein the recovery device includes solid-liquid separation means for solid-liquid separation of the precipitate in the desorption liquid and the desorption liquid by a filter press method. A phosphorus recovery method for recovering phosphorus from phosphorus-containing water,
A phosphorus recovery method including at least a residue removal operation, a membrane filtration operation, an adsorption operation, and a recovery operation.   The phosphorus recovery method according to claim 7, wherein the residue removal operation includes a step of removing residue with a drum-type screen.   The phosphorus recovery method according to claim 7 or 8, wherein the adsorption operation includes a step of adsorbing phosphate ions in the phosphorus-containing water to an adsorbent containing an inorganic ion adsorbent. In the recovery operation,
Desorbing phosphate ions from the adsorbent with a desorption liquid;
Adding a deposition agent to the desorption solution;
The method for recovering phosphorus according to claim 9, comprising a step of stirring the desorption liquid.   The phosphorus recovery method according to claim 9 or 10, comprising a step of washing the adsorbent with an acidic aqueous solution in the adsorption operation.   The phosphorus recovery method according to claim 10 or 11, comprising a step of solid-liquid separation of the precipitate in the desorption liquid and the desorption liquid by a filter press method in the recovery operation.

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